Fix multiple SIP realtime issues

1. Set lastms to 0 when clearing instead of ""
2. Don't set ipaddr or port to the string "(null)" when they are empty
3. Add missing required fields, set default for lastms to 0, and modify
   the length of the ipaddr field to 45 in the Postgresql realtime.sql
   file.

(closes issue ASTERISK-19172)
Review: https://reviewboard.asterisk.org/r/1703/
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Merged revisions 354348 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 354349 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@354360 65c4cc65-6c06-0410-ace0-fbb531ad65f3